Sunrise III: Data Storage Recovered

As photos from the landing site show, Sunrise III is in good shape after its stratospheric research flight. First observational data look promising.

Following the landing of the balloon-borne solar observatory Sunrise III in the Canadian Northwest Territories, the recovery team has now reached the landing site. Sunrise III has touched down in a wooded area and, at first glance, appears to be in good condition. The data storage units containing the scientific data from the Sun, which the observatory recorded during its more than six-day stratospheric flight, have already been recovered. The first raw data, which was transmitted during the flight to the mission's control center at the Max Planck Institute for Solar System Research (MPS) in Germany and used there to calibrate the scientific instruments, looks extremely promising. Sunrise III was not only able to observe several sunspots, but has also set a world record.

Sunrise III's flight lasted six days, 14 hours and 46 minutes. After weeks of waiting for favorable launch conditions, the observatory took off from the Esrange Space Center near the Swedish town of Kiruna, north of the Arctic Circle, at 6:24 a.m. (CEST) on 10 July, 2024. At an altitude of around 35 kilometers, it was caught by stratospheric easterly winds and carried over Iceland and southern Greenland to the Canadian Northwest Territories. Between the Mackenzie River and Great Bear Lake, Sunrise III made a controlled parachute descent on July 16, 2024.

Long flight duration

“We are incredibly pleased that the wind conditions in the stratosphere allowed us to fly for more than six days,” says Dr. Andreas Korpi-Lagg from MPS, the mission’s project manager. Together with the international Sunrise III team, he supervised the entire flight at the Göttingen Operations Center, the mission's control center at the MPS. Sunrise III has no propulsion system of its own; the stratospheric winds alone determine the duration and route of the flight.

The Sunrise III team is highly satisfied with the initial data, which was transmitted to Göttingen in low quality for monitoring purposes during the flight. All the scientific instruments functioned smoothly. As the Sun is currently particularly active, Sunrise III was able to observe several sunspots, dark areas on the solar surface with especially high magnetic field strength, and even a solar flare. The team also achieved a world record: a continuous observation at the highest resolution lasting for more than four hours. “We have thus achieved one of the most important technical goals of the mission,” says Prof. Dr. Sami K. Solanki, Sunrise III Principal Investigator and director at the MPS. While space observatories generally do not achieve a comparable resolution due to the significantly smaller size of their telescopes, during ground-based observations air movements in the atmosphere usually lead to interruptions after much shorter observation times. In the case of Sunrise III, a sophisticated image stabilization system ensures that the observatory captures images of the Sun with the highest precision despite the swaying motions of the gondola.

Support from the ground and from space

As part of a coordinated observational campaign, ten ground-based solar telescopes around the world, including the Daniel K. Inouye Solar Telescope (DKIST) in Hawaii and GREGOR in Tenerife, as well as the SDO, IRIS, Hinode, CHASE and Aditya-L1 space probes and satellites from the USA, Japan, China and India, kept an eye on the Sun at the same time as Sunrise III. “We are confident that in this way a unique set of data has been created that will help us to understand the nature of our star better than ever before,” says Solanki. Once the data storage units are returned, it will take several months to calibrate the data before detailed scientific analysis can begin.

Hidden in the underbrush

The first task is now to continue the recovery. The first day was already an adventure. From Yellowknife, the largest and only city in the Canadian Northwest Territories, a Cessna flight took the recovery team to the more northern community of Norman Wells. From there they continued by helicopter. “It wasn't easy to find Sunrise III,” reports Daniel Maase from the MPS, one of three MPS members of the recovery team. "We first had to fight our way about 200 meters through the underbrush to reach the parachute. It was easier to spot because of its striking orange color. And from there, the ropes holding the parachute to the observatory led us to our goal,” he adds. One of the team's first tasks was to retrieve the data storage devices. These contain Sunrise III's most valuable cargo: the scientific data recorded by the three scientific instruments during the flight. The recovery team has already removed the data storage units and transported them back to Norman Wells.

Over the next few days, the team will now remove and secure components of the telescope, the scientific instruments and other hardware parts and dismantle the gondola. The freight will then be transported to Yellowknife by helicopter and airplane. From there, the various hardware parts will then set off on their journey (some in overseas containers) to their home institutions in Germany, the USA, Spain, and Japan. The data storage units will arrive at the MPS earlier. They will travel back home in the recovery team’s hand luggage in the next few days.

The mission

The balloon-borne solar observatory Sunrise III is a mission of the Max Planck Institute for Solar System Research (MPS, Germany) and the Johns Hopkins Applied Physics Laboratory (APL, USA). Sunrise III looks at the Sun from the stratosphere using a 1-meter telescope, three scientific instruments, and an image stabilization system. Significant contributors to the mission are a Spanish consortium, the National Astronomical Observatory of Japan (NAOJ, Japan), and the Leibniz Institute for Solar Physics (KIS, Germany). The Spanish consortium is led by the Instituto de Astrofísica de Andalucía (IAA, Spain) and includes the Instituto Nacional de Técnica Aeroespacial (INTA), Universitat de València (UV), Universidad Politécnica de Madrid (UPM) and the Instituto de Astrofísica de Canarias (IAC). Other partners include NASA's Wallops Flight Facility Balloon Program Office (WFF-BPO) and the Swedish Space Corporation (SSC).
Sunrise III is supported by funding from the Max Planck Foundation, NASA under Grant #80NSSC18K0934 and #80NSSC24M0024 (“Heliophysics Low Cost Access to Space” program), and the ISAS/JAXA Small Mission-of-Opportunity program and JSPS KAKENHI JP18H05234. The Spanish contributions have been funded by the Spanish MCIN/AEI under projects RTI2018-096886-B-C5, and PID2021-125325OB-C5, and from ”Center of Excellence Severo Ochoa” awards to IAA-CSIC (SEV-2017-0709, CEX2021-001131-S), all co-funded by European REDEF funds, “A way of making Europe”.